package sun;

import java.util.HashMap;
import java.util.Map;

import java.util.HashMap;
import java.util.Map;


public class MapTest {
	public static void main(String[] args) {
		Map<String,Object> map = new HashMap<String,Object>();
		
		map.put("1", null);
		map.put("2", null);
		System.out.println(map.containsKey("2"));
	}
}
